(1) Field of the Invention
The present invention relates to a new and useful device for controlling the amount of a gaseous fuel supplied to an appropriate fuel burner. Whereas the conventional approach to this function makes use of a machined orifice spud or orifice hood, with the metering orifice per se usually being a drilled (or otherwise machined) hole, the present punched orifice inspirator may be advantageously constructed from a short length of small diameter tubing with a plurality of suitably formed, punched openings around the periphery of the tube. Advantages of this device over the conventionally drilled or machined orifice include:
1. Lower cost. PA1 2. A great reduction in the burner throat length required for fuel-air mixing and establishment of a satisfactory mixture flow profile. PA1 3. The ability to inexpensively incorporate more than one set of orifices in a single part to allow its use on multiple fuel types and supply pressures. PA1 4. The ability to economically pre-set the fuel-air ratio injected into the burner throat for more than one fuel type at time of manufacture. If desired, this pre-setting ability can, in many cases, obviate the need for additional (and costly) air control devices, e.g., shutters, sleeves, and the like. PA1 5. Injection of more primary air into a short throat burner, than a drilled orifice can inject into a similar burner of conventional throat length. PA1 Hawk: no. 973,040 PA1 Deforest: no. 991,141 PA1 Needham: no. 1,411,062 PA1 Beckman: no. 2,187,010 PA1 Ferrel: no. 2,513,087 PA1 Wright: no. 2,631,659 PA1 Lovett: no. 2,785,742 PA1 Anderson: no. 3,233,654 PA1 Guth: no. 3,816,061
(2) Description of the Prior Art